HOME VULNERABILITIESCVE-2021-33477

HIGH

CVE-2021-33477

CWE-755Published: May 20, 2021· Updated: Jun 17, 2026

8.8

CVSS v3.1

Official Description

rxvt-unicode 9.22, rxvt 2.7.10, mrxvt 0.5.4, and Eterm 0.9.7 allow (potentially remote) code execution because of improper handling of certain escape sequences (ESC G Q). A response is terminated by a newline.

Technical Analysis

CVE-2021-33477 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.8.

CVSS v3.1 Vector Breakdown

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges Req.Low

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

Debian1 product(s)

debian linux

eterm_project1 product(s)

eterm

Fedora1 product(s)

fedora

mrxvt_project1 product(s)

mrxvt

rxvt_project1 product(s)

rxvt

rxvt-unicode_project1 product(s)

rxvt-unicode

Source: NVD CPE · 7 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time

Offensive Security exploit database

GitHub PoC Search

Community PoC repositories

Rapid7 / Metasploit

Metasploit module search

Security advisories & exploits

Official NIST entry

CVE Program entry

External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttp://cvs.schmorp.de/rxvt-unicode/src/command.C?r1=1.582&r2=1.583

PATCHhttp://cvs.schmorp.de/rxvt-unicode/src/command.C?r1=1.582&r2=1.583

ADVISORYhttp://cvs.schmorp.de/rxvt-unicode/Changes?view=log

ADVISORYhttps://git.enlightenment.org/apps/eterm.git/log/

ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/05/msg00026.html

ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/06/msg00010.html

ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/06/msg00011.html

ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/06/msg00012.html

ADVISORYhttps://packetstormsecurity.com/files/162621/rxvt-2.7.0-rxvt-unicode-9.22-Code-Execution.html

ADVISORYhttps://security.gentoo.org/glsa/202105-17

ADVISORYhttps://security.gentoo.org/glsa/202209-07

ADVISORYhttps://sourceforge.net/projects/materm/files/mrxvt%20source/

ADVISORYhttps://sourceforge.net/projects/rxvt/files/rxvt-dev/

ADVISORYhttps://www.openwall.com/lists/oss-security/2017/05/01/20

ADVISORYhttps://www.openwall.com/lists/oss-security/2021/05/17/1

ADVISORYhttp://cvs.schmorp.de/rxvt-unicode/Changes?view=log

ADVISORYhttps://git.enlightenment.org/apps/eterm.git/log/

ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/05/msg00026.html

ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/06/msg00010.html

ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/06/msg00011.html

ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/06/msg00012.html

ADVISORYhttps://packetstormsecurity.com/files/162621/rxvt-2.7.0-rxvt-unicode-9.22-Code-Execution.html

ADVISORYhttps://security.gentoo.org/glsa/202105-17

ADVISORYhttps://security.gentoo.org/glsa/202209-07

ADVISORYhttps://sourceforge.net/projects/materm/files/mrxvt%20source/

ADVISORYhttps://sourceforge.net/projects/rxvt/files/rxvt-dev/

ADVISORYhttps://www.openwall.com/lists/oss-security/2017/05/01/20

ADVISORYhttps://www.openwall.com/lists/oss-security/2021/05/17/1

All References (40)

→

http://cvs.schmorp.de/rxvt-unicode/Changes?view=logThird Party Advisory

→

http://cvs.schmorp.de/rxvt-unicode/src/command.C?r1=1.582&r2=1.583Patch · Third Party Advisory

→

https://git.enlightenment.org/apps/eterm.git/log/Third Party Advisory

→

https://lists.debian.org/debian-lts-announce/2021/05/msg00026.htmlMailing List · Third Party Advisory

→

https://lists.debian.org/debian-lts-announce/2021/06/msg00010.htmlMailing List · Third Party Advisory

→

https://lists.debian.org/debian-lts-announce/2021/06/msg00011.htmlMailing List · Third Party Advisory

→

https://lists.debian.org/debian-lts-announce/2021/06/msg00012.htmlMailing List · Third Party Advisory

→

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6RFMU5YXXNYYVA7G2DAHRXXHO6JKVFUT/

→

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AO52OLNOOKOCZSJCN3R7Q25XA32BWNWP/

→

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DUV4LDVZVW7KCGPAMFZD4ZJ4FVLPOX4C/

→

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NZWGE2RJONBEHSPCBUAW72NTRTIFKZAX/

→

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SLPVEPBH37EBR4R54RMC6GD33J37HJXD/

→

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UXAKO6N6NKTR6Z6KVAPEXSZQMRU52SGA/

→

https://packetstormsecurity.com/files/162621/rxvt-2.7.0-rxvt-unicode-9.22-Code-Execution.htmlExploit · Third Party Advisory · VDB Entry

→

https://security.gentoo.org/glsa/202105-17Third Party Advisory

Quick Facts

CVE IDCVE-2021-33477

CVSS Score8.8 / 10

SeverityHIGH

WeaknessCWE-755

CISA KEVNo

Affected6 vendor(s)

PublishedMay 20, 2021

Related CVEs (CWE-755)

Recommended Actions

→Apply vendor patches immediately
→Monitor CVE-2021-33477 in threat intel feeds
→Review IDS/IPS signatures for exploitation attempts

Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.

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